Kamen Rider Build: The Stranded Scientist
by JikanNoEiyu
Summary: Born into a new world after the success of his suicide attack against Evolt that took their lives, Kiryu Sento now lives his life in the world of Remnant, becoming Kamen Rider Build to protect it!
1. エボルトは星を狩る

**Kamen Rider Build: The Stranded Scientist  
Episode [tan(45)]: ****エボルトは星を狩る**

 _ **-**_ _ **エボルトは星を狩る**_ _ **-  
\- Eboruto wa Hoshi o Karu -  
\- Evolt Hunts the Stars -**_

 **Sento:** Civil war breaks out over Pandora's Box and the massive amount of energy within it. Kamen Rider Build, Kiryu Sento is completely defeated by the overwhelming power of Evolt, who fused with Kamen Rider Cross-Z, Banjo Ryuga. And finally, Evolt opens Pandora's Box!  
 **Kazumi:** Kamen Rider Build, the end! Starting this week, it'll be a love story between Kazumin and Miitan, called "Love and Date the Idol Otaku"!  
 **Sento:** No, it won't! Besides, you've already mentioned the same thing in the other recap! Why am I even using the old recap to begin with?! Anyways, what'd you go and come up with a title for? You never even answered my question earlier!  
 **Kazumi:** We're in a different show after all!  
 **Sento:** New name then! Build is still the lead character in episode 1 of Kamen Rider Build: The Stranded Scientist! Hell, it's even in the title. Let's begin!  
 **Kazumi:** How are we even speaking English to begin with?

* * *

"Now Nanba's waging a war against the world? I was right." Evolt merely laughed at Sento's struggle, fighting in TankTank Form whilst Evolt continued to utilize his newly-earned second phase, EvolDragon. Utilizing the Beat Closer summoned through his armour, he pulled on the end of the weapon once, preparing an attack.

 **[HIPPARE! SMASH HIT!]**

As Sento fell down backwards, having been clearly nearly drained of his stamina, Evolt simply continued his rant on humanity's greed. "There's no limit to the greed of humanity, and that's not even including your foolishness." As Sento struggled to stand up after having been attacked, he simply gritted his teeth, stating, "That's not true! We'll put an end to this useless war!" Sento then took out the Pandora Panel FullBottle that he had made the previous night, about to utilize its power, before he stared at it, reminiscing at the words that Misora had told him before he charged into battle, when she found out about its effects.

 _"Why can't I get through to you? Why don't you value yourself more?" He only remembered himself comforting Misora's cries, as he tried to reassure her the best he could that the war would finally end._

Sento, having finally stopped grieving at the sadness he'd bring to Misora, only stated to himself, with her in mind, "Sorry... I have to protect everyone and bring peace back. Nothing is more important than that..." As Sento focused on the situation at hand, Evolt having not attacked him yet, he then took out the FullFull RabbitTank Bottle from the Driver, readying the Pandora Panel FullBottle, as he shoved it into the Driver, the gyro on the belt flashing a steady stream of white, and the Panel coursing multiple colours as it awaited his transformation.

As he began to pull on the crank of the Driver, the effects of the FullBottle began to take control of him, causing multiple blue jolts of electricity to begin coursing through the Build Driver, and subsequently into the Ride Armour, causing Sento to scream in pain. Evolt had merely stared on at Sento's transformation as he continued pulling the crank, the jolts of electricity continuing to take control of his body. However, gaining his resolve, Sento painfully responded, "Build Up!" as he readied himself for his next move. Unleashing all of the built-up electricity that had been coursing through his body, the electricity would be unleashed all around Sento, causing miniature explosions, as Evolt slashed the ones heading in his direction using the Beat Closer.

"This is..." Evolt noticed something off with Sento's upgraded transformation, as he stared onto Sento, who had been walking towards him, seemingly rejuvenated as if his previous attacks on Sento weren't having any effect on him. As Evolt sent the blade down onto Sento's shoulder, it merely collided, letting out tiny sparks; however, Sento didn't budge, causing Evolt to suddenly stop his attack in surprise, also gaining the attention of Kazumi, who had just finished defeating his fair share of Clone Smash and Hard Guardians.

And on command, Sento then punched Evolt with a force hard enough to land him in the nearby body of water, along with his blade. Sento merely stared at Evolt, a newfound strength showing itself, as Kazumi could only ask in shock to himself, "What's going on?" As Evolt crawled out of the small body of water, he'd merely comment on Sento's newfound strength, "Hazard Level 6. So you've finally surpassed human limits?" As he sat up, gaining his composure back, he'd merely continue his statement, "Well done, Sento. So you're another one of those foolish humans."

As Sento stared on, he simply asked regarding Evolt's sudden statement, "What do you mean?" Evolt then stood up, facing in Sento's direction as he then asked, "Why do you think I caused this war?" He stared at Sento maliciously as he then replied to his own question, "So I could use you to restore my own power!" As Sento gasped, on the road to realizing the truth about something far more malicious than he imagined, Evolt took out the incomplete Evol-Trigger, holding it in his left hand, as he then continued his talk, "For a human, there's a limit to how much of the energy in this that can be used." Walking towards Sento, he would then continue, "That's why I took advantage of the power of science. If a war began, you'd have no choice but to strengthen the Rider System, whether you liked it or not."

Sento then realized the truth behind Evolt's continuous asking of him upgrading, even before he knew of his true identity, and he stared at his own armour, reminiscing on the major upgrades the Rider System had undergone ever since he first gained many months prior to the present.

 _The FullBottle purifications that he, Soichi and Misora had been doing before the reveal of Soichi's true identity as Blook Stalk and subsequently Evolt, in particular the Touto set of FullBottles._

 _ **[HAGANE NO MOONSAULT! RABBITTANK! YEAH!]**_

 _The creation of the RabbitTank Sparkling FullBottle, utilizing the RabbitTank Best Match and the Pandora's Box FullBottle, and subsequently its first usage against Blood Stalk in the alleyway he had been 'found' at by Evolt._

 _ **[SHUWATTO HAJIKERU! RABBITTANK SPARKLING! YEA-YEAH!]**_

 _The Hazard Trigger that Evolt had given him which had come with massive strength, and berserker-murderer effects, and subsequently his first fight with it against the multiple Hard Smash that Hokuto's prime minister, Yoshiko Tajimi, had sent at him and Banjo back when Touto and Hokuto were at war with each other._

 _ **[UNCONTROL SWITCH! BLACK HAZARD! YABEI!]**_

 _The FullFull RabbitTank Bottle that he had created to overcome the berserker effects of the Hazard Forms, the speedy RabbitRabbit Form and its first usage during the 3-on-3 battle with Seito, the strong TankTank Form and its first usage to defeat Rogue during the same battle._

 _ **[KURENAI NO SPEEDY JUMPER! RABBITRABBIT! YABEI! HAEI!]**_

 _ **[KOTETSU NO BLUE WARRIOR! TANKTANK! YABEI! TSUEI!]**_

 _And lastly the Pandora Panel FullBottle that he was currently using, made from compressing a panel of the Pandora's Box to fit the Build Driver._

He could hear the transformation sounds accompanying each memory that he had of the powers that he had created, either as Sento, or as Takumi. Evolt then continued with his speech, "And with this power, you would become the ultimate Kamen Rider. That's what Project Build really was about!" As Sento stared at Evolt's grinning form, anger and hatred slowly seeping its way into his mind, he then barked back, "You caused a war for _that_?! What bullshit!" Dashing towards him, Sento would try to punch him with the newfound strength that he still supposedly had, only to be met with sparks forming from Sento punching Evolt's face, before he then flash stepped out of the way, punching Sento in the armour at the gut, and causing a hole to form in the armour, Evolt's hand inside it. Evolt merely taunted Sento's failure, "Too late! Everything went as planned!"

Sento stared at Evolt, unable to anything, the feeling of losing his own life force present. Kazumi, on the other hand, was horrified at the scene unfolding in front of him, and he dashed towards Sento and Evolt, screaming, "Evolt's fist is in Build!" As Evolt began to absorb the power of both Sento and Build, he'd then state, "I shall take Build, who has surpassed human limits and become complete!" Absorbing the power of Build, multiple surges of energy would fill Evolt's armour, and with that, suddenly, Ryuga's body would fall backwards, Evolt finally no longer possessing him. As Sento saw what had happened then, he simply grinned, painfully laughing, as he then stated, "I was waiting for that."

And on instinct, Sento would then pull the crank of the Build Driver once again, no longer having intentions of holding back as the Pandora Panel continued to course through a rainbow of colours, his Hazard Level rising and Evolt looking on in confusion. Sento would then state, "Measure my Hazard Level." Evolt, hand still absorbing Build's power, retorted in shock, "What?! 6.1! 6.2! 6.3! Impossible... it keeps going up!" A large surge of energy would then be released from the Build Armour, causing Evolt to reel in pain, and Kazumi to even be pushed backwards. Sento then continued pulling the crank, as he stated, "Thanks to Dad's experimental data, I saw through your plan!"

 _He then remembered Dad's research plan, intent on creating a device that could channel the full power of Pandora's Box to help him destroy Evolt once and for all._

Sento grinned, staring at Ryuga's unconscious body as he continued to pull the crank. "I pretended to fall into your trap so I could save Banjou!" Evolt, suddenly shocked at something he hadn't expected in the slightest, then suddenly asked, "Do you know what raising your Hazard Level so quickly can do?!" Sento, finally fully at his resolve, then shouted as his free hand then latched onto Evolt's hand, "Yeah! I'll perish with you!" Sento's rapidly rising Hazard Level caused his armour to begin dissipating, and he stared into Evolt, screaming, "This is the end, Evolt!" Evolt's armour too began to dissipate, asked in anger, "A human, deceive me?! Bullshit!" He would then grab Sento's other hand, the one that he had been using to pull the crank, but Sento would grab him with his free hand, latching onto him, as a bright explosion took place, fog surrounding the explosion soon after, as Kazumi shielding himself from the explosion.

As the mist dissipated, all that was left was Ryuga's unconscious body, the Evol-Driver and the incomplete Evol-Trigger that Evolt had been using, and Sento's Hazard Trigger and FullFull RabbitTank Bottle. However, neither Sento or Evolt were present, which only meant one thing; Sento had truly defeated Evolt, but at a heavy cost... Sento had truly committed a suicide attack.

And as Sento had finally defeated Evolt, potentially bringing peace to the Earth, there was a heavy cost... his own allies would bear the burden of not being able to save him; Banjo Ryuga for not being able to do anything, having being possessed himself; Kazumi Sawatari for not saving Sento before his own suicide attack; and Misora Isurugi, Sawa Takigawa and Gentoku Himuro for being unable to fight and protecting Sento, the most affected one being Misora herself. But was it the actual end of the story?

* * *

Sento's eyes suddenly jolted open, and his mind woke up, still confused as to what the hell actually happened. His body, just as confused as his mind, gave control to his mind, removing itself from auto-pilot, as the newly-awakened Sento tried to look around him, to no avail. As he began to stand up, he fell to the ground, sitting down, as he fully gained control of his body. It felt weird, like as if he had embraced death in the arms- oh wait, he did...! He was supposed to have died fighting Evolt! And even if Sento himself didn't die, he surely didn't fight Evolt in a place full of trees; he remembered that there were buildings and stuff. But as he felt his own body, another thing, something more wrong began to surface.

"Why am I alive? Why does my body suddenly feel like I'm eighteen years old?! Why am I suddenly able to fluently speak English, a language that I can only read well but not speak?! Am I even still actually able to speak Japanese?!" Sento sighed, as he tried to get some form of Japanese out, muttering to himself, "なぜ私はここにいるのですか？(Why am I here?)" A sigh of relief came out of Sento's mouth, thankful that he was able to speak Japanese at the very least. Standing up properly this time, he looked around him, trying to figure out where the actual hell he was at.

Looking around, he deduced that he was in some form of forest, judging from the trees around him that resembled forest trees. However, they felt almost unnatural in a way that was somewhat unnerving to him; the emerald green colour of the trees almost felt odd in a way that made him feel like he was in one of those weird video games that Ex-Aid could play. Anyways, continuing to look around, he noticed a weird building in the distance, that seemed like something that was definitely not Japanese in style at all; he saw a giant tower in the distance that seemed fantasy-like, and felt like something out of the Wizard of Oz.

However, deciding that heading to that tower was the best plan of action, or rather, the only sane option that Sento had. Besides, the lighthouse-shaped design the top of the tower had could potentially signal the presence of a town of sorts there; maybe civilization of some form, a place where Sento could actually get answers. However, as he was about to head in the direction of the giant tower, he then heard growls coming from the bushes and trees all around him, which definitely freaked him out a little.

Looking for a weapon of sorts to defend his new eighteen-year-old body, he then realized that the only things present with him, which were scattered on the floor in front of him without his realization, were his Build Driver and the Rabbit and Tank FullBottles, which definitely felt odd to him. As he picked them up, he then muttered a thought to himself, "他のフルボトルはどこですか？！(Where are the other FullBottles?!)" However, it wasn't something he could ponder on for too long, as he then noticed red eyes glowing from the same trees which produced the growling noises, leading him to realize that this was something far more dangerous than what he had expected.

Deciding to do the one thing he knew very well with the tools on hand, he held the Build Driver in his hand, equipping it on his waist, as the belt straps formed, its whirring signalling the Driver coming to life. Still worried at multiple things that had nothing to do with the situation, Sento found himself having to put those away temporarily as wolf-like figures would emerge from the bushes, with a look that clearly made it such that they wanted to kill Sento. Knowing that he had to be fast, he took out the Rabbit and Tank FullBottles, as he said to himself, "さ, 実験 を 始めよう か? (Now, shall we begin the experiment?)" Shaking the Bottles as fast as he could, equations began to appear around him, in the direction of the wolf-like figures, as they began to attack. Interestingly enough, the equations would damage them, causing them to be pushed backwards, as a weird shadow-like substance leaked from them.

Catching on to the fact that these weren't just regular wolves, he then twisted the caps of the two FullBottles, the labels being displayed on the front, and the essences ready to be utilized. He then inserted the two Bottles into the two Driver slots, as emblems of a red rabbit, and a blue tank would appear in front of the Driver.

 **[RABBIT! TANK! BEST MATCH!]**

Immediately, letting out a deep breath, Sento pulled the crank of the Driver, as the RabbitTank Snap Ride Builder began to form around him, the tubes slowly beginning to fill with red and blye liquid. As the tubes fully filled up, the Rabbit and Tank Halfbodies forming on the Snap Ride Builder, Sento readied himself, as the belt chanted once more.

 **[ARE YOU READY?]**

Entering his usual transformation pose, he then shouted, "へんしん! (Transform!)" And as if on command, the two halves of the Snap Ride Builder were pulled towards, as the Halfbodies snapped together, locking and forming the armour of Build, before multiple vents of Nebula Gas were released from the armour. Readying himself, he prepared for what was essentially the first transformation he'd have in this weird place.

 **[HAGANE NO MOONSAULT! RABBITTANK! YEAH!]**

Readying himself for an interesting battle, his eyes would light up, as he then said, "の法則が決まった. (The law of victory has been decided.)" Immediately, he rushed into battle with the wolf-like figures, attacking them by punching and kicking, which seemed to do some form of harm to them. As the wolves charged at him, he jumped, landing a hit on multiple of them, before multiple tubes would then form, which interestingly enough, harmed some of the wolves before filling with red and blue liquid, similar to the RabbitTank Snap Ride Builder, forming the Drill Crusher.

 **[DRILL CRUSHER!]**

Interesting. That's never happened before. Sento made a mental note of that, before he changed the Drill Crusher into gun mode, firing away at the wolves. As the bullets clashed with the creatures, they'd be push back, signalling to Sento that it did some for good damage to them. However, apparently, it wasn't enough, as he'd be scratched by the claws of the wolves, which were definitely stronger than the normal.

As he readied the Drill Crusher, changing it into Blade Mode again, he then checked the FullBottle Holder on his belt, for any other useful FullBottles that he could use. Interestingly enough, he eyed the Harinezumi and Lion FullBottles on the Holder, as if waiting to be used. Grinning slightly as his sudden advantage, he then grabbed the Harinezumi FullBottle, shoving it into the FullBottle slot on the Drill Crusher, the emblem of a white hedgehog appearing for a few seconds, before the blade would begin spinning at a fast speed.

 **[READY, GO! HARINEZUMI! VORTEX BREAK!]**

As he slashed away at the creatures, he'd make sure to do as much damage as possible; fearing that he'd attract any more of the weird wolf creatures. And as he finished slashing, multiple white spikes would protrude from the wolf-like creatures, as they fell to the ground, beginning to fade into oblivion, surprising Sento. Deciding that their essence was worth taking, Sento looked for an EmptyBottle, before noticing two more on his holder, catching his eye. Taking one out, he'd twist the cap open before the essence of the creatures would be absorbed into the Bottle, as it changed into a blue SmashBottle.

What was also interesting was the fact that another EmptyBottle's cap was already open as well, as it absorbed a more darkened essence from the same creatures, turning into a black SmashBottle. Sento had to admit to himself, he was curious, and scared of the Bottle, to say the very least. But at least for now, the problem had been settled. As he placed the SmashBottle he was holding back into its slot, he decided to stay in armour in the event that more of them came, even if he didn't want such an event to happen.

As he made his way to the forest, heading in the direction of the tower, he found himself thinking back at the fate that the World of Build was undergoing. Even if he himself had defeated Evolt during that fateful suicide attack, there was no guaranteed method to remove the Skywalls that had formed because of the incomplete Pandora's Box's awakening, or even the Pandora Tower that had appeared due to Evolt being a little piece of shit and activating the Pandora's Box's full potential. That was even if Evolt had been truly defeated during his attack. And even if so, there was still the other issue; of Evolt's race, planet destroyers who had the power beyond anything imaginable. Or so was what Vernage had said.

 _Kazumi, walking towards Misora, asked the entity currently possessing her, Vernage, "Hey. Just who the hell is Evolto anyways?" "A lifeform from a world that this planet has yet to discover. A single member of Evolto's race was enough to destroy our planet." The three Riders were in shock at how strong Evolto truly was. "I was the only one left, and fought him, prepared to die. I damaged the Evol-Driver, and separated his body from his soul...so he used the box to store his own energy." The three Riders would stare at the Pandora's Box, with Gentoku then muttering, "Then Pandora's Box was Evolto's all along." Vernage would mutter one last sentence before stopping her possession of Misora. "Evolto must not be allowed to gain his final form."_

With how strong Evolt actually was, Sento feared of the possibility that somebody from the same species of Evolt would come to Earth to finish the job that he had started. And it might even be somebody stronger than him, somebody Sento knew all of the Riders, hell, even Vernage, couldn't even stand a chance of facing against. He just clung onto the hope that he could at least find his way home as fast as possible, if he even was in the homeworld to begin with, and potentially regroup with them.

But even if Evolt's species wasn't intent on returning to Earth to finish the job, there was still the issue that Seito had still taken over Hokuto, and was hell-bent on uniting Japan in the most twisted way possible. For one, there was Juzaburo Nanba himself, dude who is currently guising as the Prime Minister of Seito, and head behind Nanba Industries. If anything, he could easily send out orders to either make more Guardians, or stronger Guardians. Then, there were the Washio brothers; wielders of the Remocon Bros. and Engine Bros. powers, and subsequently the Hell Bros. powers (even if the Riders were mostly stronger than them); but worst of all, there was Nariaki Utsumi himself, the ultimate wild card in the system. The creator of the Nebulasteam Gun, modified from the Kaiser System, and creator of Grease and Rogue's Sclash Drivers. There was no telling of what he could actually do; hell, he could have actually managed to recreate the Evol-Driver itself, or even worse, actually use one. He was really hoping that the three Riders could handle Seito's forces.

But now, having been deep in discussion, he found himself facing the said tower that he had spotted only in the distance mere minutes ago, which somewhat surprised him. And for another, he was surprised at how short the journey it was; maybe it was closer than he first expected, perhaps? It also wasn't just a tower, it felt like an entire academy! Then, he noticed something that caught his eye.

Two individuals approached him, as he slowly took out the two Bottles from their respective Driver slots, causing Sento to de-transform as he simply observed them. The male individual seemed to be wearing an odd shade of green, with some round spectacles to boot, and seemed to be holding a mug of what was either hot chocolate, or coffee. The female individual seemed to have what looked to be a weird device that resembled a phone, but wasn't a phone by Earth standards. And as Sento finished de-transforming, he could only mutter one phrase, "Who are you two?"

* * *

\- 次回は, 仮面ライダービルド! -  
 _\- Jikai wa, Kamen Raidā Birudo! -_  
 _\- Next time on Kamen Rider Build! -_

A lost scientist stuck in a new body and in need of a way in a new world, a headmaster with hidden, yet noble and good intentions, an awkward weapon nerd idolizing fairy tales and needing new friends, a brawler whose own temper can burn brighter than her own element, and a hero whose dragon emblem begins to glow dim!

How do these tales align?! Tune in, for the (6 / 3)nd episode, of The Stranded Scientist!

 **-** **ヒーローの再開** **-  
** _ **\- Hīrō no Saikai -**_ **  
** _ **\- The Hero's Restart -**_


	2. ヒーローの再開

**Kamen Rider Build: The Stranded Scientist  
Episode [sqrt(4)]: ****ヒーローの再開**

 _ **-**_ _ **ヒーローの再開**_ _ **-  
\- Hīrō no Saikai -  
\- The Hero's Restart –**_

 **Sento:** Pandora's Box, which contains a massive amount of energy, is finally opened by the alien lifeform Evolt. Kamen Rider Build, Kiryu Sento, fights Evolt, and attempts to save a possessed Banjo, and in the end, succeeds, destroying him in an explosion that utilizes the Pandora Panel FullBottle.  
 **Sento:** However, waking up in a new world, he searches for answers, encountering the elusive creatures known as Grimm, and fending them off, as he finds himself encountering the prestigious Beacon Academy.  
 **Ozpin:** As he finds himself at the prestigious Beacon Academy, he encounters the headmaster of said academy, Professor Ozpin.  
 **Glynda:** Are you really sure that bringing in the new guy is a good idea? For one, we found him in the forest, and he doesn't know where the hell he is. Two, he's saying weird stuff that the both of us definitely don't understand.  
 **Sento:** It's you two! The people I encountered after coming out of that forest! Why the hell are the both of you here?! This recap was made for only me!  
 **Ozpin:** You'll eventually find out.  
 **Sento:** それは私が持っている奇妙な名前の大部分が正当であると私が仮定したものであることを助けるものではありません。(It doesn't help that most of the weird names I have are just things I assumed were correct.)  
 **Sento:** Anyways, let's continue with the second episode of Kamen Rider Build: The Stranded Scientist!

* * *

"Who are you two?" Sento asked as he unequipped the Build Driver, placing it into one of the pockets of his coat, as he straightened it, taking out whatever tiny twigs and leaves that had somehow gotten themselves magically attached to it. The man standing in front of him simply smiled slightly, stating, "If you want answers, I highly recommend that you follow the two of us." Sento, deciding that it was the best option, as much as he really didn't like it, as he simply replied, "Fine. But if you two decide to attack me, I won't hesitate to fight back!"

Sure, he only had four FullBottles; sure, he had only three accessible forms (one Best Match and two Trial Forms), but at least he'd been through a worse hell by now than he did when he first saved Banjo. And back then, he had what, nine FullBottles and 20 accessible forms (two Best Matches and eighteen Trial Forms). So he was pretty confident of himself, especially considering the fact that he had a pretty decent Hazard Level (4.2). And as he said that, the male simply replied with a content nod, content with his agreement, as he, and his female assistant from the looks of it, headed back into the building.

As Sento followed the two of them, keeping the Rabbit and Tank FullBottles at the ready along with the Build Driver, Sento found himself admitting that the architecture of this academy seemingly struck a chord with its majesty. It seemed to cement that something was off with this place, that Sento might have not been from this world to begin with. Maybe Sento's theory was right; maybe he was in another world, similar to how Banjo ended up temporarily during the Kaiser crisis. But forgetting that aside, he continued to follow the two of them, to where ever they were heading to.

* * *

The Pandora's Box, which contains enough energy to destroy the Earth, has finally been opened, by the extraterrestrial lifeform, Evolt! However, in a twist of events, he has been defeated by Kiryu Sento, Kamen Rider Build, through a suicide attack that takes both of their lives!

However, even if Evolt has seemingly been defeated by Sento, two worlds, Earth and Remnant, may potentially be exposed to a threat larger than what they've ever faced before! Standing up against the threats that face the two worlds, are the Kamen Riders of Earth and Remnant!

 **\- Kamen Rider Build: The Stranded Scientist! -**

 _(_ _この まま 歩き 続けている_ _~!)  
(Kono-mama aruki-tsudzuete iru~!)  
(Alone I go, down the only road I know!)_

The screen panned to a shot of Sento shaking the Rabbit and Tank FullBottles, as he stared at the camera, smiling as he continued to shake the two FullBottles. Then, it would pan to a brief shot of Sento writing down an equation based on the basic law of thermodynamics on a blackboard, before panning to multiple shots of Sento as Build with the Machine Builder in its Bike form, before showing a shot of him riding with the Machine Builder down multiple empty streets in Vale.

 _(_ _今夜 も まあすぐ_ _~!_ _ひとり の 足跡 たどって_ _~!)  
(Kon'ya mo mā sugu~! Hitori no ashiato tadotte~!)  
(Through the empty dead of night! Leaving just one trace behind, my feet in time!)_

The screen would then pan to Build as he rode his motorcycle past multiple barrages of bullets aimed at him, before panning to Build continuing to ride the bike, as portraits of multiple people panned across the screen; Banjo Ryuga doing push-ups, Misora Isurugi in her Mii-tan outfit, Sawa Takigawa in an alleyway looking for news, Kazumi Sawatari tending to his former farm in Hokuto, Himuro Gentoku walking onwards in an empty field in his Seito outfit, Ruby Rose as she was hacking away at multiple Grimm, Weiss Schnee summoning multiple glyphs with her sword, Blake Belladonna as she sat at the Beacon Academy fountain in the middle of night, and Yang Xiao Long, punching a red punching bag, then to a portrait as he rubbed his head, his hair popping upwards, before panning to him smiling at the camera, before rubbing off the equations written on the blackboard from earlier, multiple of them related to quantum physics.

 _(_ _果てしない だけど君だけは_ _~!)  
(Hateshinai dakedo kimi dake wa~!)  
(The dark is vast, I wonder just how long, I'll last!)_

Then, it would pan to a group shot of Ryuga and Yang, combat sparring and throwing punches at each other, as if in a boxing match, before panning over to Misora, as she fixed her hair and messed around with the decorations in the laboratory, before entering the purifier machine in the lab as the door would close in front of her.

 _(_ _どこかで待ってる_ _~)  
(Dokoka de matteru~!)  
(But I know that you're waiting there!)_

The shot would pan to Build, as he rode his bike past the same street from earlier, all of his allies would watch upon him. To his left, were Ryuga, Misora, Sawa, Kazumi and Gentoku, and two his right, were Team RWBY, Ruby, Weiss, Blake and Yang.

 _(_ _笑顔絶やさずに_ _~!)  
(Egao tayasazu ni~!)  
(With a smile that never wears!)_

The shot would then pan to a view of Pandora's Box, multiple hands reaching out for the Box, each hand stopping the others' from reaching it; Build, Cross-Z, Grease, Rogue and Evol's hands, before Misora's hand appeared, the golden light radiating brightly from her bangle. Then, it would pan to the interior of nascita, showcasing multiple shenanigans between Team Build and Team RWBY, panning to a shot of them holding the letters of nascita and RWBY.

 _(There you will!)_

The scene would then flash to a close-up of Misora, inside of the purification machine, her eyes turning green, as the golden bangle on her wrist began to glow. Then, the shot panned to another character, her face not present, as a golden bangle on her wrist also began to glow. Then, it panned to the lab, the purifier machine ringing as a bottle was purified.

 _(Be the One! Be the One! Alright!)_

It would then pan into a lab, not the one under nascita, as Sento and Team RWBY suddenly leaped, leaving them confused, as Sento grinned, dashing towards the lab, as he grabbed the purified FullBottle, the Rabbit FullBottle, before panning to him defeating multiple Grimm using the Drill Crusher and 4-Koma Ninpoutou, dual-wielding them.

 _(_ _明日の地球を投げ出せないから_ _~!)  
(Ashita no chikyū o nagedasenai kara~!)  
(The tears of tomorrow will be nothing but a bad dream!)_

The scene would then pan to Sento, who readied himself, as the RabbitTank Snap Ride Builder formed itself around him, and as he entered his transformation pose, the armour would form, pulling itself towards him, locking together as he transformed into Build, executing his post-transformation pose.

 _(Be the Lights! Be the Lights! Alright!)_

Then, it would pan to Build, still in RabbitTank, jumping from a hole that shot dirt through a large pillar, before the equation of his finisher formed, him immediately executing his default finisher. Then, it would pan to two split screen shots of him; one in HarinezumiTank as he sent out multiple white spikes to the camera, and one in LionTank, as he summoned multiple yellow blasts.

 _(_ _強くなれるよ_ _~!_ _愛は負けない_ _!)  
(Tsuyoku nareru yo~! Ai wa makenai~!)  
(The strength that you possess I wanna share it!)_

Then, it would pan to a shot of Cross-Z in Cross-Z Magma Form, as he readied the Cross-Z Magma Knuckle, preparing a finisher, before flames surrounded him, with him dashing towards the camera and throwing a burning punch. Then, it would pan to another split screen shot; one of Kamen Rider Rogue having completed his transformation in the dark of night, the green in his eyes turning bright, the other being Kamen Rider Grease as he stared atop of a building and watching Hokuto. Then, it would pan to a shot of the Evolt-possessed Soichi, as he transformed into EvolCobra with the Evol-Driver, multiple vents of Nebula Gas covering him in a fog-like manner.

 _(_ _何かを助けて救って抱きしめ_ _~!)  
(Nanika o tasukete sukutte dakishime~!)  
(I wanna be someone who saves the day and can embrace!)_

The screen would then pan to shot of a centrifuge containing multiple FullBottles, as Sento would take out five FullBottles from the centrifuge; a red one, a pink one, a white one, a purple one and a blue one, taking them out one by one.

 _(_ _心に触れるよ 届くよ 伝われ_ _!)  
(Kokoro ni fureru yo todoku yo tsutaware~!)  
(The lines between the dots, I'll open hearts and change their fates!)_

It then panned to Team RWBY and Sento shaking the FullBottles that he had grabbed from the centrifuge; Sento shaking the red FullBottle, Ruby shaking the pink FullBottle, Weiss shaking the white FullBottle, Blake shaking the purple FullBottle, and Yang shaking the blue FullBottle. Then, it would pan to the Skywall, as multiple equations began to break the sections of the wall. Then, it would pan to a shot of Build driving away from a giant Guardian robot, before crushing it in GorillaMond.

 _(Be the One! Be the Light!)_

As Build, still in GorillaMond, punched the giant Guardian robot, he would break its right leg, causing it to crash to the floor, as he jumped away from it, changing back to RabbitTank and continuing to ride his bike.

 _(_ _メッセージ 送るよ 響くよ_ _!)  
(Messēji okuru yo hibiku yo~!)  
(From this city to echo through the world!)_

Immediately, it would pan to a montage of Team RWBY attacking with their various weapons, before panning to a shot of Cross-Z, Grease and Rogue, as they fought multiple Smash and Guardians. Then, it would pan to an empty room, as multiple equations would fly over the top of the room, as Katsuragi and Sento would walk towards each other, Katsuragi in his lab gear, and Sento in his casual clothing. As they touched hands, Katsuragi would walk through Sento, fading into dust, as Sento would walk forward, confused, Katsuragi smiling as he faded. Then, it would pan to a shot of Sento standing in Ozpin's office, staring at Vale, as the camera would spin around him, multiple equations flying through the air.

* * *

Minutes had already passed since Sento found himself at this weird academy, and he had decided to follow two individuals who he had no knowledge or idea of. To a normal person, that would sound rather worrisome, but to Sento, he had no choice but to do so. He, after all, landed in a forest of what felt like an essentially different world. And as he found himself walking at what felt like the courtyard of the building, he observed the situation around him, hoping to get answers by doing so. And because he wasn't really the sociable type, unless people spoke about science-related stuff, he wasn't going to just ask the people around him.

From what he could find from his observations, the name of this place seemed to be 'Beacon Academy', evident from a giant signboard on the front of the building that literally had it emblazed with giant letters that allowed you to see its name from many miles away, or that's what Sento assumed from his calculations anyways. And judging from the name of the building, containing the word 'Academy' in it, he assumed it was an educational institution of some kind, a place of learning of sorts. Besides, that's what he assumed based on the schools he had seen in Touto to begin with.

Although, the fact that the students weren't wearing a uniform outfit, instead choosing to wear their own clothes, seeming individualistic, did catch Sento off-guard. However, he just shrugged it off as being a university of some kind, since those things did allow students to wear anything they wanted. So technically, his theory still stood. Until he considered the fact that they weren't carrying any bags of some kind; he assumed they would have bags of some kind, considering this was a school and all.

But what they did have on their belts would give Sento an immediate run for his money; most students had what looked to be weapons of multiple varieties, ranging from what looked like swords, to what looked like pistols. It did frighten Sento, but it proved his other world theory even more. Maybe this was a world where war was a thing, more common than war actually was on Earth itself... that frightened Sento more than it originally should have, and he could understand why. That day... he still remembered it vividly, haunting him even though Kazumi forgave him...

 _Knocked out of transformation from his first debut as RabbitTank Hazard, Sento held his head from the headache. As Sento groaned to get up, he saw the scene unfolding around him, as his mind began to break down. He saw Aoba, Kazumi's friend from the Three Crows, beginning to dissipate, as Kazumi would hold him tight, screaming, "Hey! Hey! Hey, hey! Pull yourself together!" As Aoba began to dissipate, still in his Hazard Smash form, he stated, "I'm worried... If I'm not around, you can't do anything, Boss..." As he grasped his dog tag with his right hand, he removed it from his chain, giving the label to Kazumi, saying, "No matter what happens, we're together..." He disintegrated into a cloud of blue dust, as Sento was in tears. As he frantically searched for an answer, he asked in a pure panic, "Did I do it..?"_

That day. The day he killed somebody for the first time. He hated it. It brought nightmares to him. It practically screamed at Sento, laughing at him for falling victim to such an act. A tiny tear shed from his eye, as he put the memory aside, focusing on continuing to garner more information from the surroundings around him. And judging the situation at hand, the weapons on the students' belts seemed to hint that this was an academy of sorts that trained some form of combat.

But what kind exactly? Maybe multiple questions with the two individuals he was following would help him find more necessary answers. As he continued to follow the two of them, he then noticed the students greeting the two individuals in front of him as 'Headmaster' and 'Professor', which interested him greatly. So maybe the male was the headmaster of this 'Beacon Academy'? The thought of it did come as a surprise to him; maybe, just maybe, the headmaster might offer him an invitation into this academy. However, it did seem far-fetched, as he did seem like a person who came out from nowhere; there was no way a headmaster would accept him into an academy.

But one more worrying thing crossed his mind; how were the other Riders on Earth faring?

* * *

It had been many hours since Grease and Sento had left the nascita building to rescue Ryuga from his possession by the cosmic abomination known as Evolt, and the two female heroines who had stayed behind, mainly due to either their inability to fight, or Vernage being an asshole, were horribly worried at the fates of the three Riders. Gentoku hadn't been able to fight, mainly because Grease had given him time to think about his current situation, and to let him garner his resolve to fight Evolt for the greater good.

As he rested in the lab, in the spare bedroom, Misora and Sawa were waiting, their imaginations, influenced by the events that they had gone through, had run wild, thinking up of nightmarish situations that flooded their minds, and began to scare them. What if Grease and Sento were unable to rescue Ryuga? What if they were killed by Evolt? What if Ryuga was killed by Evolt, and he possessed Sento or Grease? The questions, it scared them. And it would make them dissociate enough to surprise them when the door to the building suddenly opened.

Not the fridge door, but the main door itself.

Was it them? Did they make it out alive? Did they save Ryuga? As Misora continued to shiver from worry, Grease entered, still wearing his Sclash Driver, as he brought in along with him, a weak Ryuga, who definitely lacked the look of when Evolt had possessed him, and more resembled his previous self. On instinct, Misora greeted the two of them, stating, "Welcome back." As the two entered the cafe, they would close the door behind them, as Sawa then noticed something off.

Where was Sento? Where was Sento? Where was Sento?! Why hadn't he returned as well? Sento wasn't missing, right? He definitely wasn't missing, right? Sawa then asked, fear crossing her mind, "Kazumi, where's Sento? And what happened to Evolt?" Kazumi flinched slightly, a look of sorrow crossing his expression, as he stated, "He managed to defeat Evolt, but he..." Kazumi couldn't bring himself to say the words that he needed to say, mainly because he knew how Misora would react; the pain his words would bring to her. Sawa froze, realizing what his sorrowful expression meant.

"He's dead, isn't he?" Sawa asked Kazumi, as Misora froze even more, in shock and in pure agony. The tears in her eyes began to well, as she began to cry. Kazumi looked downwards, laying Ryuga on one of the chairs, as he replied, "Yes." Misora collapsed onto the ground, holding her eyes as tears began to flow from her eyes. She had reminded Sento on what would happen if he used the Pandora Panel. She asked Sento on why he didn't value himself; a question he never gave an answer to. He had only fought in the name of love and peace. And it would come to haunt her for days on end.

* * *

An odd feeling of sorrow washed over Sento's expression, before he realized what he was feeling. This was what everybody on Earth was feeling. The combined sorrow had somehow managed to affect him, and he realized why. Misora's tears were powerful. And as he found himself looking at the sky, he only said to himself.

 _"_ _ごめんなさい。_ _(I'm sorry.) But I did what had to be done. In the name of love and peace."_

As Sento focused himself, wiping off the tear that had suddenly appeared on his eye, he found himself outside of the 'Headmaster's Office', looking up to see the two individuals in front of him unlocking the entrance door to the office. So, his theory was somewhat right to an extent. This man really was the Headmaster of Beacon Academy, and he was interested to see what would happen. Although, a smile didn't really form on his face because of what he had felt mere seconds ago. As the two entered the office, he would follow along, slowly stepping into the room, as he closed the door behind him, taking a chance to observe the room around him.

And he had to admit; this room had definitely chosen to use an odd design, the circular design of the room clearly influenced by the fact that this was a tower, and this office was on the exact top floor of the said tower. Another interesting thing was the aggressive usage of the clockwork motif in the building, consisting of multiple gears on the top half of the room, which also seemed to actually function, for some bizarre reason. It was as if the Headmaster liked time for some reason. Maybe for that same reason, he'd love to use the Watch FullBottle, if Sento even knew where it was to begin with. Most likely, it'd be in the Pandora's Box. Besides, that was the last place he knew where most of the FullBottles were to begin with. It also gave him a hint of confusion; as if there were other Kamen Riders who possessed the power of time.

* * *

Somewhere in Japan in 2016, a certain CEO who had taken over a company previously owned by his son for some reason sneezed. It was as if somebody was talking about him, in a different time and place. But he decided to forget it as he continued scheming his evil plans, checking on the status of the Doctor Riders.

Somewhere else, also in Japan, in 2018, a certain high school student who aspired to become a king also for some reason sneezed. He had been sneezing a bit too much; maybe he had a cold or something like that. He should really check with the doctor or something like that.

And somewhere else, somehow also in Japan, in 2002, a card glowed slightly.

* * *

Eh, maybe Sento was just confused to begin with. Shrugging off his confusion aside, he came to when he noticed the headmaster dude snapping his finger, pointing at the chair at the desk in front of him, signalling to him to take a seat. Sento did so, pulling his chair backwards, taking a seat, before the headmaster caught his attention, beginning the conversation. "So, first, I highly recommend you calm down. Maybe you know why I told you to follow the two of us, or do you not?" Sento calmed down slightly, still worried about Misora's condition, as he replied, "I don't know, honestly." The male then introduced himself, "First, let's get introductions out of the way. I'm Professor Ozpin, headmaster of Beacon Academy, and this is my assistant, Professor Glynda Goodwitch."

Sento resisted the temptation to snort. If he ever found Ryuga again, this was how he was going to introduce him, while fighting as Build and Cross-Z. 'I'm Kiryu Sento, and this is my assistant, Banjou Ryuga.' That would sound pretty neat, especially considering that it sounds science-like and all. Then, Sento replied, simply to be polite, "Kiryu Sento, Kamen Rider Build." Ozpin then seemed to make a mental note of what he had said, before he continued, "So, Kiryu Sento, let me ask you one thing, considering you're a random stranger who seemed to come out of the Emerald Forest. What were you doing there?"

The 'Emerald Forest'? So that was the name of the weird forest that he landed out in? Maybe that explained why the trees in the forest took an unnatural shade of emerald green; the forest must have been named after the tree colours. Sento then responded, "How am I supposed to know? I just... suddenly woke up there." Ozpin then stroked his chin, oddly similar to how Gentoku would back when he was Night Rogue, and he then responded, "Now, tell me, can you explain this?" Immediately, his assistant, Professor Glynda, would then take out what appeared to be a phone of some sorts, displaying footage that Sento immediately recognized.

It was footage somehow gained of his transformation into Build, and his subsequent fight against the weird wolf-like creatures from earlier. For one, how did they get ahold of footage like that? Sento was very sure of something regarding earlier, to begin with. "しかしどうですか？間違いなくドローンやカメラはどこにもなかった。 (But how? There definitely weren't drones or cameras anywhere.)" Sento needed to get his concerns out in the open at this point, asking Ozpin, "How did you get your hands on footage like that?" Ozpin simply responded, "I have my ways. But there's one thing I must confirm with you on something like that."

And he placed his hands on the table, like a boss, and asked, "What is that system of yours? I've never quite seen anything like it." Sento simply gritted his teeth, responding, "The Rider System, also known as the Build Driver. A transformation device used to transform into Kamen Rider Build, the one you see in the footage." Ozpin then immediately asked afterwards, "Build?" Sento simply responded. "Yes. Build, as in 'to create' or 'to form'." A catchphrase he learned from Katsuragi after he had found out the data regarding Project Build a very long time ago. Ozpin then noted, "Interesting. A device that seems like it comes from another world."

Another world? So it really was like the Kaiser crisis after all. He truly was in another world; although, this one seemed much more different than the world Ex-Aid and all the other Kamen Riders he had met had resided in. This one seemed much more fantasy-like, as if it came straight out of a cartoon of some sorts. He couldn't really bring a connection, so he'll just put that aside for the time being. He then suddenly questioned, "So, tell me, Sento, have you ever heard of Remnant?"

Remnant? Was it the name of this world? Sento might as well reveal that he's from another world; no matter how far-fetched it actually sounds. "Remnant, as in the noun?" Ozpin simply stated, "No. As in the place." The place? That was where Sento was in? Interesting. Sento then stated, "No. I've never heard of Remnant. Why do you ask?" A wave of curiosity flashed by Ozpin's face, as he then muttered to himself, Glynda overhearing him, "Our prediction was right. He really is from another world."

As Ozpin began to think about something, Sento decided to use his short time to review the Kaiser situation, to help jog his memory somewhat; it was like his amnesia began acting up again long after he had found out of his identity as Takumi. He remembered Ex-Aid, Emu Hojo as he called himself, and his special power that helped Sento greatly during the crisis; Muteki, invincibility. There was also his counterpart, Parado, who had somehow managed to search for Build for two very long years. Besides that, there were the other Kamen Riders who had fought long before Sento and Emu ever had; Kamen Rider Ghost, Takeru Tenkuji; Kamen Rider Gaim, Kouta Kazuraba; Kamen Rider Fourze, Gentaro Kisaragi; and Kamen Rider OOO, Eiji Hino.

He also remembered the main villain that him and the other Riders had faced; Kaisei Mogami, the former mentee of Katsuragi, and the creator of the Kaiser System, a device that combined Nebula Gas with an otherworldly substance known as Nebula Gas, and using the Engine and Remote Control Gears to transform into Kaiser and Bikaiser for one and both sides respectively; a device that would eventually be re-created by Utsumi, into the Nebulasteam Gun, and the Remocon, Engine, and Hell Bros. There was also Enigma, the device Kaisei used to try and merge the two worlds together, which Katsuragi had also used to get Ex-Aid's essence.

Ozpin then stated, "Based on the data we have gathered, and your answers to my questions, I would like to offer a deal." Sento then sat up straight, his eyebrows raising in confusion, as Ozpin then continued, "As you might have already guessed by now, from your observations that I have noticed, that I am Ozpin, the headmaster of Beacon Academy." Okay, Sento knew that. What was going on? What was Ozpin intending? He then continued, "I would like to extend a personal invite to you into Beacon Academy myself. Judging from your strength and 'powers' as 'Kamen Rider Build', it seems like you will be a necessary and helpful ally."

Okay, Sento was taken by surprise by that one. And an offer into what essentially was an educational institution? Of course Sento was going to accept it! And he was going to need to take as many chances and opportunities as he needed to, in order to survive in what essentially was another world, a new place. But then suddenly, Ozpin's assistant, Professor Glynda Goodwitch from what he heard mere seconds ago, then retorting at Ozpin's claim, "Isn't your decision a little too sudden? You allowed Ruby Rose in just for trying to stop a Dust robbery the other day, and you're suddenly allowing this teenager, somebody we know completely nothing about, into the academy?"

Ozpin simply grinned, replying, "Fine, if that's what you wish; if you really want to keep an eye on the kid so much, I'll add another offer then." He then faced towards Sento, continuing, "I'll offer you another deal at the same time. I would like to extend an invitation for you to become both a student, and a teacher at the same time." And Glynda's reaction was surprisingly shocking. She hadn't expected this! But well, Sento was still going to take his chance, even if it meant him being a teacher. "Deal." And the two males smiled, slightly.

And then, Ozpin stated, "Now, considering that you're from another world, you don't really have any of this world's currency. So we might as well give you some Lien, this world's currency." Taking out multiple coloured cards which seemed to have metal strips on them, similar to credit cards, he would pass them to Sento, as he picked them up, examining them. "That's 1000 Lien. Feel free to do whatever you want in the two to three days before school begins the year." Sento smiled, "Got it!"

And with that, Sento stood up, smiling as he left the office, deciding to figure out where to go. But before that, Sento asked, "So where are the shops and all?" Ozpin pointed in a general direction, south of where the tower was, and Sento headed off, in journey of his next goal; getting enough stuff to potentially last him the whole school year. Ozpin stood up, watching Sento as he left the building, before he could only say to himself, "Who are you exactly, Kiryu Sento...? And as Sento left Beacon, he gazed into the horizons for the fun of it, simply stating, with a smile on his face, "さ, 実験 を 始めよう か? (Now, shall we begin the experiment?)"

* * *

\- 次回は, 仮面ライダービルド! -  
 _\- Jikai wa, Kamen Raidā Birudo! -_  
 _\- Next time on Kamen Rider Build! -_

A scientist trapped in a new body with a new story to tell; two different hot-headed fighters with temper and power levels that seem to keep increasing, a young girl with big dreams for a bright future, and a runaway whose identity is masked in the simplest of ways!

How do their stories intertwine?! Tune in, for the [sqrt(9)]rd episode, of The Stranded Scientist!

 **-** **ストーリーが絡み合う** **-  
** _ **\- Sutōrī ga Karamiau -  
\- Stories Intertwined -**_

* * *

And now, it's time for me to address the five reviews I have gotten for the last chapter!

 **reynardgautama:** Thanks for the compliment!  
 **merendinoemiliano:** I have a lot planned with the RWBY plot, and the other Riders!  
 **RocketFourze:** Eheh! Thanks! :D  
 **Cross-Z Magma:** Got it! I'll make sure to do that!  
 **Xivitai (Guest 1):** Perhaps. Perhaps not.

And now, ciao~!


	3. ストーリーが絡み合う

**Kamen Rider Build: The Stranded Scientist  
** **Episode (n = 3):** **ストーリーが絡み合う**

 ** _\- ストーリーが絡み合う -  
_** ** _\- Sutōrī ga Karamiau -  
_** ** _\- Stories Intertwined -_**

 **Sento:** Last time, on Kamen Rider Build: The Stranded Scientist; the genius physicist, Kamen Rider Build, Kiryu Sento, has found himself in the 'elusive' land of Remnant, where he finds himself encountering the headmaster of the 'elusive' Beacon Academy, Professor Ozpin, and his assistant, Glynda Goodwitch, landing a place in the prestigious Beacon Academy.  
 **Blake:** And soon, he'll find himself in deeper trouble then he was first expecting; not only is he present in the World of Remnant, but the Smash and potentially have appeared as well.  
 **Sento:** Excuse me, but who are you?! And how do you seem to know about the Smash as well?!  
 **Blake:** You'll find out this episode. Now get to it; the recap can't last too long, like last time.  
 **Sento:** Could you, like, stop breaking the fourth wall?! Anyways, here's the third episode of Kamen Rider Build: The Stranded Scientist! Don't miss it!

* * *

As Sento headed out of Beacon Academy, the first order of business that Sento had on his mind, was to head into the city centre, to look for the supplies he needed, not as a genius physicist, but also as a school student. Deciding that it was best to head there by bike, and judging from the distance that Ozpin had stated mere minutes ago, he searched for the Build Phone, hoping his best that it was among the stuff that had been thrown into Remnant along him. And to his luck, he found the Build Phone attached to his belt, sighing in relief.

Taking the phone out, he would then take out the Lion FullBottle, before inserting it into the slot of the phone, allowing the phone to change into its Bike Mode, as he grinned slightly.

 **[BUILD CHANGE!]**

Riding the bike, he'd pull up the centerstand using his left foot, before pressing a button on the HUD present on the bike where the details such as the fuel tank and current speed would be, before a helmet would materialize, Sento immediately putting it on. Heading into the city center, Sento would look around him, observing the buildings and architecture around him. And as he arrived in the city centre of what apparently was called Vale, a very odd choice of name for a very odd choice of city, as he then began looking around, unaware of the fate that would be intertwined between him and somebody else.

* * *

The Pandora's Box, which contains enough energy to destroy the Earth, has finally been opened, by the extraterrestrial lifeform, Evolt! However, in a twist of events, he has been defeated by Kiryu Sento, Kamen Rider Build, through a suicide attack that takes both of their lives!

However, even if Evolt has seemingly been defeated by Sento, two worlds, Earth and Remnant, may potentially be exposed to a threat larger than what they've ever faced before! Standing up against the threats that face the two worlds, are the Kamen Riders of Earth and Remnant!

 **\- Kamen Rider Build: The Stranded Scientist! -**

 _(この まま 歩き 続けている~!)  
_ _(Kono-mama aruki-tsudzuete iru~!)  
_ _(Alone I go, down the only road I know!)_

The screen panned to a shot of Sento shaking the Rabbit and Tank FullBottles, as he stared at the camera, smiling as he continued to shake the two FullBottles. Then, it would pan to a brief shot of Sento writing down an equation based on the basic law of thermodynamics on a blackboard, before panning to multiple shots of Sento as Build with the Machine Builder in its Bike form, before showing a shot of him riding with the Machine Builder down multiple empty streets in Vale.

 _(今夜 も まあすぐ_ _ひとり の 足跡 たどって_ _~!)  
_ _(Kon'ya mo mā sugu~! Hitori no ashiato tadotte~!)  
_ _(Through the empty dead of night! Leaving just one trace behind, my feet in time!)_

The screen would then pan to Build as he rode his motorcycle past multiple barrages of bullets aimed at him, before panning to Build continuing to ride the bike, as portraits of multiple people panned across the screen; Banjo Ryuga doing push-ups, Misora Isurugi in her Mii-tan outfit, Sawa Takigawa in an alleyway looking for news, Kazumi Sawatari tending to his former farm in Hokuto, Himuro Gentoku walking onwards in an empty field in his Seito outfit, Ruby Rose as she was hacking away at multiple Grimm, Weiss Schnee summoning multiple glyphs with her sword, Blake Belladonna as she sat at the Beacon Academy fountain in the middle of night, and Yang Xiao Long, punching a red punching bag, then to a portrait as he rubbed his head, his hair popping upwards, before panning to him smiling at the camera, before rubbing off the equations written on the blackboard from earlier, multiple of them related to quantum physics.

 _(果てしない だけど君だけは~!)  
_ _(Hateshinai dakedo kimi dake wa~!)  
_ _(The dark is vast, I wonder just how long, I'll last!)_

Then, it would pan to a group shot of Ryuga and Yang, combat sparring and throwing punches at each other, as if in a boxing match, before panning over to Misora, as she fixed her hair and messed around with the decorations in the laboratory, before entering the purifier machine in the lab as the door would close in front of her.

 _(どこかで待ってる~!)  
_ _(Dokoka de matteru~!)  
_ _(But I know that you're waiting there!)_

The shot would pan to Build, as he rode his bike past the same street from earlier, all of his allies would watch upon him. To his left, were Ryuga, Misora, Sawa, Kazumi and Gentoku, and two his right, were Team RWBY, Ruby, Weiss, Blake and Yang.

 _(笑顔絶やさずに~!)  
_ _(Egao tayasazu ni~!)  
_ _(With a smile that never wears!)_

The shot would then pan to a view of Pandora's Box, multiple hands reaching out for the Box, each hand stopping the others' from reaching it; Build, Cross-Z, Grease, Rogue and Evol's hands, before Misora's hand appeared, the golden light radiating brightly from her bangle. Then, it would pan to the interior of nascita, showcasing multiple shenanigans between Team Build and Team RWBY, panning to a shot of them holding the letters of nascita and RWBY.

 _(There you will!)_

The scene would then flash to a close-up of Misora, inside of the purification machine, her eyes turning green, as the golden bangle on her wrist began to glow. Then, the shot panned to another character, her face not present, as a golden bangle on her wrist also began to glow. Then, it panned to the lab, the purifier machine ringing as a bottle was purified.

 _(Be the One! Be the One! Alright!)_

It would then pan into a lab, not the one under nascita, as Sento and Team RWBY suddenly leaped, leaving them confused, as Sento grinned, dashing towards the lab, as he grabbed the purified FullBottle, the Rabbit FullBottle, before panning to him defeating multiple Grimm using the Drill Crusher and 4-Koma Ninpoutou, dual-wielding them.

 _(明日の地球を投げ出せないから_ _~!)  
_ _(Ashita no chikyū o nagedasenai kara~!)  
_ _(The tears of tomorrow will be nothing but a bad dream!)_

The scene would then pan to Sento, who readied himself, as the RabbitTank Snap Ride Builder formed itself around him, and as he entered his transformation pose, the armour would form, pulling itself towards him, locking together as he transformed into Build, executing his post-transformation pose.

 _(Be the Lights! Be the Lights! Alright!)_

Then, it would pan to Build, still in RabbitTank, jumping from a hole that shot dirt through a large pillar, before the equation of his finisher formed, him immediately executing his default finisher. Then, it would pan to two split screen shots of him; one in HarinezumiTank as he sent out multiple white spikes to the camera, and one in LionTank, as he summoned multiple yellow blasts.

 _(強くなれるよ_ _愛は負けない_ _~!)  
_ _(Tsuyoku nareru yo~! Ai wa makenai~!)  
_ _(The strength that you possess I wanna share it!)_

Then, it would pan to a shot of Cross-Z in Cross-Z Magma Form, as he readied the Cross-Z Magma Knuckle, preparing a finisher, before flames surrounded him, with him dashing towards the camera and throwing a burning punch. Then, it would pan to another split screen shot; one of Kamen Rider Rogue having completed his transformation in the dark of night, the green in his eyes turning bright, the other being Kamen Rider Grease as he stared atop of a building and watching Hokuto. Then, it would pan to a shot of the Evolt-possessed Soichi, as he transformed into EvolCobra with the Evol-Driver, multiple vents of Nebula Gas covering him in a fog-like manner.

 _(何かを助けて救って抱きしめ_ _~!)  
_ _(Nanika o tasukete sukutte dakishime~!)  
_ _(I wanna be someone who saves the day and can embrace!)_

The screen would then pan to shot of a centrifuge containing multiple FullBottles, as Sento would take out five FullBottles from the centrifuge; a red one, a pink one, a white one, a purple one and a blue one, taking them out one by one.

 _(心に触れるよ 届くよ 伝われ_ _~!)  
_ _(Kokoro ni fureru yo todoku yo tsutaware~!)  
_ _(The lines between the dots, I'll open hearts and change their fates!)_

It then panned to Team RWBY and Sento shaking the FullBottles that he had grabbed from the centrifuge; Sento shaking the red FullBottle, Ruby shaking the pink FullBottle, Weiss shaking the white FullBottle, Blake shaking the purple FullBottle, and Yang shaking the blue FullBottle. Then, it would pan to the Skywall, as multiple equations began to break the sections of the wall. Then, it would pan to a shot of Build driving away from a giant Guardian robot, before crushing it in GorillaMond.

 _(Be the One! Be the Light!)_

As Build, still in GorillaMond, punched the giant Guardian robot, he would break its right leg, causing it to crash to the floor, as he jumped away from it, changing back to RabbitTank and continuing to ride his bike.

 _(メッセージ 送るよ 響くよ_ _~!)  
_ _(Messēji okuru yo hibiku yo~!)  
_ _(From this city to echo through the world!)_

Immediately, it would pan to a montage of Team RWBY attacking with their various weapons, before panning to a shot of Cross-Z, Grease and Rogue, as they fought multiple Smash and Guardians. Then, it would pan to an empty room, as multiple equations would fly over the top of the room, as Katsuragi and Sento would walk towards each other, Katsuragi in his lab gear, and Sento in his casual clothing. As they touched hands, Katsuragi would walk through Sento, fading into dust, as Sento would walk forward, confused, Katsuragi smiling as he faded. Then, it would pan to a shot of Sento standing in Ozpin's office, staring at Vale, as the camera would spin around him, multiple equations flying through the air.

* * *

It had been a full day since Kazumi and Ryuga had returned from their fight with Seito's troops, the Hard Guardians and Clone Smashes, and the rescue of Ryuga from the possession of Evolt. However, it had also been a full day since Sento had sacrificed his own life to defeat Evolt himself, and the effects of his death still lingered amongst the nascita crew. It was a pain that was hard to describe, something even words couldn't describe.

The only one who had felt such a pain, was Kazumi. He was the only person in the nascita crew to have actually lost somebody dear to him, a pain which he had felt even more than Misora after she had found out that her 'dad' was Blood Stalk, and by extension, Evolt. The Hokuto Three Crows were the subject in particular. He still vividly remembered the moments that had led to the deaths of them; memories which would continue to haunt him, even if he had 'moved on', even if he had looked back at them for motivation to continue fighting.

Akaba, no, Masaru Ooyama, the leader of the Hokuto Three Crows, who had been killed by Rogue back when he was still 'brainwashed' by Seito's forces, during his protection of the Pandora's Box. Aoba, Syuuya Aikawa, who had been killed by Sento during his first transformation into Hazard Form, and had been overpowered by the berserkness that Sento had suddenly gone in said form. And lastly, Kiba, Syoukichi Mihara, who had taken a direct blast from one of Remocon Bros.' finishers in order to protect Kazumi and Akaba. A silent tear fell down his eye, as he stared at their dog tags, stating to himself, "I really can't do anything without you guys, huh."

The five individuals were still in mourning, with no intentions of fighting for now, even with the war between Touto and Seito still going on outside of nascita. They still had many other bigger matters to handle when the time came, like the fact that only Kazumi and Ryuga still had the ability to fight, the fact that Namba was definitely still alive, and the fact that Utsumi was the wild card in all of this. As Ryuga continued eating his second instant ramen pack of the day, he found himself staring at the Evol-Driver that Evolt had dropped after his death, deciding that maybe he would maybe formulate a plan.

* * *

Entering Vale, Sento would arrive in the city center, before changing the Build Phone back into Phone Mode, placing both the Lion FullBottle, and the Build Phone into one of his many coat pockets. Deciding that searching for toiletries and food would be a good idea, he would de-materialize his helmet, to the sudden surprise of some of the people around him, before he entered a nearby supermarket, grabbing a trolley, and looking around for everything he needed. Looking around in the supermarket, he swore that he could suddenly hear multiple people screaming outside, something he didn't hear at all before he entered.

And he was right, as he then witnessed multiple people panicking and screaming, as they ran from what seemed to be something attacking them. Shocked, Sento would keep the Build Driver at the ready, as he would leave his trolley there, dashing outside of the supermarket, and watching what in the actual hell was going on. As he noticed multiple civilians running away, more than what he had originally assumed to be, he then noticed the creature that had been attacking the civilians. It can't be...! A blue and gray Smash...! Similar to the one that Sento and Ryuga encountered during their time in Hokuto; the one that his mom, Kyoka Katsuragi, was turned into! And there was a figure in white and black trying to attack it as well! The figure, a female from the looks of it, seemed to be holding a sword in her hand, as she attacked the Smash, swinging around similar to Indiana Jones.

 **[DRILL CRUSHER!]**

However, from the looks of it, the Smash seemed to overpower her, sending her flying backwards as it continued attacking the surrounding area around it. Sento had no choice, but to equip the Build Driver, rushing towards the lady in black and white that had been thrown aside, as he helped her up, her just managing to stir to consciousness. He would then ask her, summoning the Drill Crusher, "Are you okay?" Changing the Drill Crusher into Gun Mode and firing away at the Smash, catching its attention and distracting it from its attack phase, the lady would stir to consciousness as she replied, "I'm fine... Who are you?"

Continuing to fire with the Drill Crusher in Gun Mode, Sento would then take out the Lion FullBottle, shaking it and twisting the cap, the label facing forwards, before shoving it into the FullBottle slot on the Drill Crusher, readying a mini-finisher that could at least do some damage to the Smash while he would help the lady up. "Kamen Rider Build, Kiryu Sento." The lady would then perk her head in pained confusion, as he then readied his aim, a yellow aura forming around the Drill Crusher, as he fired away at the Smash, multiple yellow blasts would be fired away at the Smash, sending it back, as Sento would help the lady up. "Blake. Blake Belladonna." Sento looked back at her, as the two got up, as he then stated, "Considering that you're in no state to fight, go help the civilians! I'll fight the Smash!" As Blake managed to stand up, she'd question to herself very briefly on what the Smash was, before heading to help some of the civilians that had been caught in the crossfire.

Sento would stand up, the Build Driver still equipped, as he took out the Lion FullBottle from the Drill Crusher, and the Tank FullBottle, knowing full well what to do, as Blake would dash around the area, rescuing the multiple civilians that had been caught in the crossfire. Sento would then drop the Drill Crusher for the time being, before beginning to shake the two FullBottles, the equations forming around Sento causing the Smash to redirect its attention towards Sento and begin dashing towards it. However, the equations seemed to harm the Smash as they got in its way, similar to when Sento was fighting the wolf creatures.

Then, to the surprise of Blake, and the civilians that had been saved, Sento would then twist the caps on the Bottles, the labels forming on the caps of the Bottles, as Sento then said his pre-battle catchphrase, "さ, 実験 を 始めよう か? (Now, shall we begin the experiment?)" Then, he would slot the two Bottles into their respective Driver slots, the emblems of a yellow lion and a blue tank forming in front of the Driver temporarily, as Sento readied himself.

 **[LION! TANK! TRIAL MATCH!]**

Hang on, was that normal for the Driver to announce whenever two Bottles would form a Trial Match? That definitely wasn't normal, and Sento made a mental note to analyze the Build Driver in its current state later, to see if there was anything different with the Driver. Putting that aside, he would then begin to pull the crank of the Driver, as the LionTank Snap Ride Builder began to form around him, the tubes slowly beginning to fill with yellow and blue liquid. As the tubes fully filled up, the Lion and Tank Halfbodies would then form in front and behind of him on the Snap Ride Builder, as Sento readied himself, the belt chanting.

 **[ARE YOU READY?]**

Entering his transformation pose, he shouted, "へんしん! (Transform!)" And on command, the two halves of the Snap Ride Builder were pulled towards him, the Halfbodies snapping and locking together to form Build's armour, before multiple vents of Nebula Gas were released from the interlocking sites. The Trial Form jingle would then play, as Sento picked back up the Drill Crusher which he had dropped earlier, changing it into Blade Mode as he readied himself.

And to the continued amazement of Blake, and the civilians that she was saving, Sento would then state, dashing towards the Smash, "の法則が決まった! (The law of victory has been decided!)" And as Sento readied his attack mode, he would prepare the Drill Crusher, utilizing it to hack and slash away at the Smash, causing it to be sent backwards, as Sento observed the situation with Blake. The good thing was that everybody had been taken care of and were a good distance away from the Smash itself. Deciding to utilize his suit as a weapon as well, something he rarely did nowadays, he dashed towards the Smash, impaling his blade into it as he used the roller shoes on his Tank Half to attack it, sending it flying away, as Sento grinned slightly.

Deciding that it was now the best time to finish off the Smash, Sento would take out the Harinezumi FullBottle, shaking it rapidly, then twisting the cap such that the label would face the front, before shoving it into the FullBottle slot on the Drill Crusher once again, before changing it into Gun Mode as he readied a blast attack.

 **[READY, GO! HARINEZUMI! VORTEX BREAK!]**

Then, he would fire multiple white spikes at the Smash, which would collide with its armour, sending it backwards, as it took a good amount of damage, to the joy of Sento, who had decided to execute one more finisher for good measure, he would take out the Harinezumi FullBottle from the Drill Crusher, placing it back in its slot on the FullBottle Holder, before de-summoning the Drill Crusher, it turning back into the tubes that had originally constructed and summoned it.

Then, Sento would state, as he readied himself to pull the crank, "これを終える時です! (It's time to finish this!)" Then, he would begin pulling the crank, as a graphing equation would begin to form, trapping the Smash in one of its lines, and catching the attention, and confusion, of many of the civilians which hadn't moved, due to their injuries. And what was the graphing equation in particular? Well, it was the sine equation, _0.5 sin (x/4)_ , which was just right enough for Sento to fire a cool blast, but not too sharp to the point that the blast could miss.

 **[READY, GO! VORTEX ATTACK!]**

And as Sento readied his second finisher, a yellow blast forming on the gauntlet weapon that came attached with the Lion Half, which had apparently been given the name of the 'Gold Lio Gauntlet' according to the specifications of the LionCleaner Form that had been recorded in the Project Build data that he had received from his mother after an intense battle with Night Rogue and Blood Stalk, he would then unleash it on the Smash, the blast following the graph's trajectory, before colliding with the Smash's armour, causing it to explode, as it fell to the floor, the Smash slowly turning back into its human host. Noticing a new EmptyBottle on the FullBottle Holder, he would take it from its slot, and twist the cap, opening the Bottle, and absorbing the radiating essence from the defeated Smash.

The human host falling onto the ground, Sento would rush towards him, still transformed, as he managed to catch him, at the very least softening his fall. As he stirred into consciousness, Sento would ask him, as Blake dashed towards the two males, "Do you remember anything that happened?" He would simply state, "I was in a tank... there were people wearing white coats. And then, there was a man wearing a bat suit." The two standing, they, along with Blake, would send the man to the hospital, as Sento was deep in thought, de-transforming back into civilian form. "バットスーツの男? それはできません! (A man in a bat suit? It can't be!)"

Something just doesn't add up properly! Not only does Faust somehow exist in this universe, with Sento knowing full well that it was most likely disbanded following the Hokuto-Touto war, because of how Gentoku was technically exiled out of the country, Nariaki having been killed, and revived somehow, and Evolt was busy making everyone declare war on each other, but Night Rogue existed in this universe, and Sento was only just now made aware of it. And judging from the scared, but not too surprised reactions, this wasn't the first time that Faust has sent out a Smash to attack the general public. Did Sento have something to do with its existence? And if Sento was right, did Takumi exist in this universe as himself, before he became Sento himself?

But as Sento realized something else, his mind paused; if Faust had sent out Smash before to attack the citizens, how was Ozpin and Glynda both unaware of the existence of Faust, considering that Ozpin looked like a man of high being? Or was there something else he wasn't stating to him? However, forced to put his thoughts aside for the time being, the two fighters would drop off the Smash host at the hospital, knowing that there was nothing better that could be done about him; even if something felt wrong about the whole thing. And Sento did realize what it was; the Smash host remembered what had happened to him, even though he became a Smash. That was only a feat achievable by those who naturally had a Hazard Level of more than two when they were experimented on, a case examples being both Ryuga and Sento. However, in that case, they wouldn't be Smashes either, which clearly wasn't the case right now. There were so many facts that contradicted each other, which greatly confused Sento.

However, he would be snapped out of his stupor, when Blake waved her hand in front of him, asking him, "You mind if we go grab some tea? You owe me an explanation." A sigh washed over Sento's face as he shrugged in agreement, the two deciding to head to a nearby tea shop that Blake had recommended. Odd, Sento couldn't understand why she immediately treated him like a friend of sorts. It was if it wasn't supposed to be this way originally. Walking towards the store, which was nearer than he first imagined, the two would take a seat, before they ordered their drinks, Blake asking Sento, "Now, explain to me everything."

* * *

As Ryuga, Misora, Kazumi, Sawa and Gentoku continued to mourn for their loss of Sento in nascita, out of the blue, an announcement from the Seito forces would play on the television screen, catching them by surprise, as Nanba, still disguised as Mido announced, "Kamen Riders of Touto, if you continue refuse to fight in this war, no matter what your reason, we shall conquer Touto-" As Misora instinctively turned off the television because of her current state of mourning, cutting the announcement short, Ryuga and Kazumi would take their Drivers, before heading out, with Gentoku forced to stay behind still due to his injuries, which were hopefully going to be healed by the following day.

As the two untransformed Kamen Riders arrived onto the scene, they noticed multiple Hard Guardians and Clone Smashes firing multiple blasts at the Touto civilians, as they could then sense the panic coming from them. Rushing to save them, they would then be stopped by the two Washio brothers, who would walk amongst the mist coming out from the bullets that had been fired by the Guardians. The two Riders readying a fighting stance, Fu would then state, "Fancy seeing you here, Cross-Z and Grease. Where's your beloved Build?" Then, Rai would take out the Nebulasteam Gun, and his Engine Gear from his arm strap, before shoving it into the gun slot, as the emblem of a white engine formed, firing a blast of Nebula Gas around the two Brothers, as the whirring sound of an engine would play.

 **[GEAR ENGINE! FUNKY!]**

Then, Fu would take the Gun from Rai, after he had taken out his own Gear, before he would then take out his Remocon Gear from his arm strap, before shoving it into the same gun slot, as the emblem of a blue-green remote control formed, continuing to fire another blast of Nebula Gas, which would surround the two, as the sounds of a remote control would play, before they would transform, stating, "Jundou," as multiple white and blue gears would form, forming their armour.

 **[GEAR REMOCON! FUNKY!]**

 **[REMOTE CONTROL GEAR! ENGINE RUNNING GEAR!]**

The 'boldness' of Fu to simply insult Sento would cause Ryuga's temper to spike up almost instantaneously, as the two Riders would then take out their respective Drivers, equipping them as Ryuga stated, "I won't let you insult Sento! Not on my dying grave!" Taking out the Magma Knuckle, the Dragon Magma FullBottle and the Robot SclashJelly, the two would then insert their respective trinkets into their Driver slots, the emblems of a orange dragon and a black robot forming.

 **[BOTTLE BURN! CROSS-Z MAGMA!]**

 **[ROBOT JELLY!]**

As the two Brothers would watch on, Fu equipping the Nebulasteam Gun and Rai equipping the Steam Blade, Ryuga would pull the crank on his Driver, the lack of a Snap Ride Builder noticeable from a mile's distance, as Kazumi would press the lever on his Driver, as oddly enough, a beaker forming around him as it filled with black liquid, something obviously normal for the transformation, as it would then form his armour. And as the two entered their transformation poses, they screamed, "Henshin!"

 **[ARE YOU READY?]**

 **[TSUBURERU! NAGARERU! AFUREDERU! ROBOT IN GREASE! BURAAA!]**

A new problem would emerge, as Ryuga did not transform into his usual state of Cross-Z Magma, the Build Driver refusing to outright work as it would catch the attention of all the combatants, who would obviously notice Ryuga frantically trying to pull the crank as he would scream at Kazumi, "Why?! Why can't I transform?!" As Kazumi would rush into battle, fighting against the two Bros., and summoning the Twin Breaker, a light bulb would flicker in his head, ever so slightly. "Ryuga! Do you remember when you found out that you were not human?" Ryuga's face lit up in confusion, as he remembered what Sento had stated.

 _"W-what do you mean that I'm not human?!" Misora would restrain Ryuga, telling him to calm down, as Ryuga would push her aside, mentioning, "I can't calm down! And you believe it?!" Sento then stated, "It explains some things." "Huh?!" "Pandora's Box. Nothing happens when we touch it, but when you touched it, the walls moved... Stalk has the same power... That means you-" Ryuga then held out his hands, screaming, "W-w-wait! Master obtained his power from Mars, right?"_

 _"Then I must have gotten my special power when they experimented on me!" Sento then refuted Ryuga's claim, stating, "Not likely. The fact that you were born only two months after conception proves that." Looking at Sawa's laptop, which contained his data, Sento continued, "You returned to normal growth levels after birth, because the alien lifeform's powers were reset when you were born. But judging from how quickly you raised your Hazard Level, it is possible that you're not a hu-" Sento was cut off by Ryuga slamming the laptop shut, stating with an angry tone, as he left nascita, "I have no idea what you're talking about."_

"B-but you weren't definitely there, right?! And also the fact that I'm a part of Evolt..." Ryuga continued, remembering what Evolt had said.

 _As Ryuga would encounter Evolt, who had promised him that if he would help remove Sento's poison if he showed him the location of the Pandora's Box, Evolt would then state, "I can't believe you're trying to save someone who tried to kill you." Ryuga would then ask, looking at him, "What do you mean?" Evolt would then ask, "You still don't know the truth behind the murder you were accused of, right?" Ryuga's eyes raised slightly, confused, as Evolt continued._

 _"Of course, it's true that Sento was Katsuragi Takumi. It's also true that I killed Sato Taro and swapped their faces. But my motive was not what you think." Ryuga looked up, as he muttered, "Motive?" Evolt would then tell the truth behind Katsuragi's murder, stating, "I didn't wipe Katsuragi's memory because he tried to quit Faust. It's because he realized our true identities." Ryuga then asked, still confused, "'Our'? What do you mean?" "I told you before."  
_

 _Ryuga then remembered what Stalk had told him. "Your power is the same as mine. It is for destroying the world." Evolt would then give his explanation for that statement, "We are one. We are the same lifeform." Pointing his finger at Ryuga, he would continue, "You were once a part of me. That means our genes combined, is the REAL EVOLT." Ryuga's body would freeze at the revelation, as he asked to himself, "What the hell? You think I'd fall for that?!" "Of course not. After all, you've lost your memory."_

 **[SCRAP FINISH!]**

Sending the two Bros. flying backwards with a finisher, which unfortunately wasn't able to send them flying and untransforming, Kazumi would then put two and two together, screaming at Ryuga from his position, "Evolt must have reabsorbed all of his genes back when he had possessed you!" As Ryuga would realize what Kazumi meant, whilst the Bros. got back up, a loud gasp escaped his mouth, along with the screams of, "No way!"

* * *

As Blake and Sento finished up with their tea, which had unsurprisingly gone cold, Sento would explain to Blake everything he knew about the story, i.e. before arriving in Remnant; starting from Vernage's sealing of Evolt, and the devastation of Mars; to Evolt's arrival to Earth, Ryuga's mother's possession, and his birth one month later; to Evolt's possession of the astronaut Soichi Isurugi, an individual involved in a project known as Project Prominence; to the discovery of the Pandora's Box on Mars, and the Skywall Disaster which took place thirteen years following Evolt's arrival, which caused the rise of the Skywall, separating Japan into three; to the beginnings of Faust, led by Katsuragi Takumi, who created the Build Driver, and various other devices; to his memory loss into his current state, Kiryu Sento, and being 'found' by Soichi and Misora Isurugi; to his first fight as Kamen Rider Build; to his meetings with Ryuga Banjou and Sawa Takigawa; to the Touto-Hokuto and Touto-Seito wars, which included his interactions with Kazumi Sawatari, Kamen Rider Grease, and Gentoku Himuro, Kamen Rider Rogue; to the rising of Kamen Rider Evol; and lastly, Sento's suicide attack against him.

As Blake would seem deeply invested in Sento's story, Sento himself would notice it, prompting an idea of maybe making it into a book or television series in Remnant, with different actors for obvious reasons. However, as he noticed Blake's suspicion of his story, Sento would then take out the Build Driver, and the FullBottles and SmashBottles he had, stating, "It wouldn't really make sense for me to make thirty minutes worth of lies just to convince one person." And as she nodded, she then asked Sento, "So, how'd you find your way into Vale then? For a person from another world like you, you suspiciously seem to have easily found your way here." Sento then explained to her the events that transcribed for him in Remnant; from his encounter with the wolf-like creatures, which Blake had confirmed the name in the recap that he had said one chapter ago, as the Grimm; to his encounter with Professor Ozpin and Glynda Goodwitch, to his acceptance into Beacon Academy, to him ending up here.

Blake would then state, after hearing Sento saying that he had been accepted into Beacon, "So, you're going to Beacon Academy as well? Interesting." Sento perked up hearing that Blake was also going to Beacon Academy, besides him, and that at least there was somebody he knew there. "So where are you going to stay for the night, considering that the first day of school is technically tomorrow?" Sento then shrugged, stating, "I don't really know. I was just expecting to sleep on one of the benches near the giant statue, I guess-" Yeah, Sento didn't really think this one through, did he? Blake would then stop him, stating, "I have a place you could stay at for one night." Sento's eye raised, as he realized what he meant, bowing politely and offering his thanks to the young lady, "Although, I came here to get groceries. I'm going to have to do that first if that's fine with you?"

"Yeah, I'm okay with that." A grin formed on Sento's face, as he said to himself, "これが一番! (This is the best!)"

* * *

 _\- 次回は, 仮面ライダービルド! -_  
 _\- Jikai wa, Kamen Raidā Birudo! -_  
 _\- Next time on Kamen Rider Build! -_

A scientist with new goals and new plans, a general lurking in the shadow of a bat, two sisters with different ideologies and styles, a heiress who just seems to not be able to cut her tongue, and a new ally whose bow oddly twitches!

Now, the stage is set for fate to take its course! Tune in, for the (4/1)th episode, of The Stranded Scientist!

 **\- アンブロケンウィル -**  
 ** _-_** ** _Anburoken'uiru -  
\- Unbroken Will -_**

* * *

And now, review time, baby!

 **Chapter 1 Reviews:**

 **Guest 2:** Not to be hating or anything, but I will ensure you that the phrase 'Transform' is there because of translation purposes only. The Japanese characters does spell out 'Henshin'.

 **Chapter 2 Reviews:**

 **merendinoemiliano:** Yep! Expect the Earth Kamen Riders to get hopefully the same amount of writing time as the Remnant crew!  
 **Cross-Z Magma:** Of course! What's Build without its famous scientific formulae? Expect to see more, but not ones that you're familiar with!

And now, ciao~!


End file.
